Konza Prairie Research Natural Area, 916 acres (370.9 hectares) of unplowed native bluesteam prairie, 10 miles south of Manhattan, Kansas, was purchased in 1971 by The Nature Conservancy and given to the Kansas State University Endowment Association for ecological research. The objective of management is to approximate the pre-white-man prairie ecosystem. Fires in that system were caused by lightning and Indians. Although lightning occurs primarily during the growing season, lightning storms have been recorded every month of the year. Spring has a slightly higher incidence of lightning than autumn. A burning plan has been developed for Konza Prairie with four replications of six treatments: unburned, burned in late April at 1-, 2-, 4-, and 10-year intervals, and burned after years when precipitation was at least 1.2 times the mediam. These treatments include the possible range of fire occurrence in pre-white-man times, so they should allow us to assess both the ways fire affects prairie and the frequencies that result in perpetuating prairie in good condition